Diamond drill and method of making the same



Dec. 26, 1933.

G. F. TAYLOR DIAMOND DRILL AND METHOD OF MAKING THE SAME Original Fi ledApri'l 2:5, 1929 Invehtor George F Taylor,

His Attorney.

' due to the great Patented Dec. 26, 1933 UNlTED STATES 1,941,288DIAMOND DRILL AND METHOD OF MAKING THE SAME George F. Taylor,Schenectady, N. 1L, General Electric Company,

New York Application April 23, 1929, Renewed January or to a corporationof Serial No. 857,587 29, 1981 9 Claims. (01. 76-108) The presentinvention relates to diamond drills and the like. Heretofore such drillshave been made by casting metal around spaced diamonds so that thediamonds protrude slightly from the metal matrix. When constructed inthis manner however, the diamonds easily become loosened difference inthe coeflicient of and the cast metal matrix. Even though the loosenessis at first of a very small degree, it tends to increase very rapidlywith any strain on the diamonds and finally results in the diamondcracking or becoming lost.

In my copending application Serial No. 357,536, filed April 23, 1929,and entitled Abrading tools, I have disclosed and claimed a compositionconsisting of diamond particles and a binder material such for exampleas tungsten carbide and cobalt.

It is one of the objects of the present invention to provide a diamonddrill in which the diamonds or cutting means are securely andpermanently anchored in a sintered metallic matrix having a coefiicientof expansion within the elastic deformation range of diamond, that is,the matrix can expand more or less with respect to the diamonds withoutcausing the latter to become strained beyond their elastic limit.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. The inventionitself however will best be understood from reference to the followingspecification when considered in connection with the accompanyingdrawing in which Fig. 1 is a view partly in section and partly inelevation of a mold whereby my invention may be carried into effect;Fig. 2 is a plan view of the lower portion of the mold; Fig. 3 is anexploded perspective view of the mold and a pressure applying member;while Fig. 4 is a perspective view, partly broken away, of a completeddrill.

Referring more particularly to the drawing, I have indicated at 1 thebottom plate of a mold. The plate 1 has a recessed portion 2, a centralcountersunk portion 3, and a plurality of smaller countersunk portions 4within which diamonds 4' may be positioned adjacent the periphery of therecess 2. The successive countersunk portions 4 are staggered so thatalternate portions are located on the circumference of a circle having adiameter somewhat smaller than the diameter of recess 2', while theremaining portions expansion of diamond ly beyond the periphery ofrecess 2. The bottom plate 1 of the mold is made of carbon and providedwith a pair of oppositely disposed upwardly projecting pins 5 adapted toengage cooperating openings 6- in the upper carbon plate 7 of the 0mold. Plate 7 is provided with a central opening 8 which is in alignmentwith recess 2 when plate '7 is so positioned on platel that pins 5engage the opening 6.

A carbon plug 9, which has a central project- 55 ing pin 10 adapted toengage the countersunk portion 3 of plate 1, extends through opening 8and rests on the surface of recess 2 providing in this manner an annularor cylindrical space 11 between the plug 9 and the walls of opening 8 7and rece 2, as clearly indicated in Fig. 1.

In manufacturing a drill according to my process, the diamonds areplaced in the small countersunk portions 4 and the plate 7 and plug 9properly positioned on plate 1. A powdered mixture consisting largely oftungsten-carbide but containing from a to 25% cobalt a then placed inthe annular space 11 so that the powdered material extends substantiallyto a point adjacent the upper surface of the carbon plate '1. so Acarbon ring 12 is then inserted in the opening 11 and a pressure ofabout 1000 pounds per square inch applied to the upper end of the ring12 while the powdered material is simultaneously heated to its sinteringtemperature by means of 5 an electric current supplied to it throughtermin'als 13 and 14 which may be clamped to the mold in any convenientmanner. The mixed powdered materials are plastic at their sinteringtemperature and flow around the diamonds making intimate contact withthem and holding them rigidly and permanently in position. The sinteredannular matrix 15 may then be brazed, welded or secured in any suitablemanner to a steel shank 16. The alternate diamonds 4' project 5 inwardlyand outwardly beyond the inner and outer circumferences of the sinteredmatrix 15. This arrang ment requires that the carbon mold be broken iorder to remove the matrix and attached diamonds therefrom. The cost ofthe 10 carbon mold is relatively small and its loss therefore is oflittle consequence.

The powdered mixture employed to produce the metallic matrix issubstantially the same as that disclosed in the patent to Schrtiter No.1,549,615 and in general consists of a carbide of an element of the 6thgroup of Mendelejei'fs periodic table and an auxiliary metal of the irongroup, such as cobalt. Instead of a powdered mixture consisting oftungsten-carbide and cobalt. I may 11c employ a mixture consisting ofthe three elements tungsten, carbon and cobalt and sinter them underpressure in the same manner as the tungsten-carbide and cobalt.

In the present application the word "diamond means a diamond ofsubstantial size as distinguished from diamond powder. By the expressionfspaced diamonds" I mean diamonds spaced out of contact with each other.

What I claim as new and desire to secure by Letters Patent oi. theUnited States, is:

1. A drill comprising a. sintered, hollow cylindrical matrix, aplurality. of spaced diamonds embedded in and protruding from the edgeportion of said matrix, said matrix consisting mainly oia carbide of ametal 01 the 6th group of Mendelejeffs periodic table.

2. A drill comprising a sintered, hollow cylindrical matrix, a pluralityof spaced diamonds embedded in and protruding from the edge portion ofsaid matrix, said matrix consisting mainly of tungsten-carbide butcontaining an appreciable amount of cobalt.

3. The method of forming a diamond cutting tool which comprises pressinga powdered mixture consisting largely of tungsten-carbide and cobaltaround a plurality of spaced diamonds, while said powdered materials aretering temperature.

4. A drill comprising a sintered hollow cylindrical matrix, a pluralityof spaced diamonds embedded in and protruding from the edge portion ofsaid matrix, said matrix consisting mainly of a carbide of a metal ofthe 6th group of Mendelejefis periodic table but containing an apheatedto their sinpreciable amount than the carbide.

5. A drill comprising a sintered hollow cylindrical matrix, a pluralityof spaced diamonds embedded in and protruding from the edge portion oi.said matrix, said matrix consisting mainly of tungsten carbide butcontaining an appreciable amount of metal of the iron group.

6. A diamond cutting tool consisting of a matrix and a plurality ofdiamonds embedded in and protruding from said matrix, substantially allof said diamonds being positioned in one plane, said matrix consistingof a cemented carbide.

7. A diamond cutting tool consisting of a matrix and a plurality oidiamonds embedded in and protruding i'rom said matrix, substantially all01' said diamonds being positioned in one plane, said matrix consistingmainly oi cemented tungsten carbide.

8. A diamond cutting tool consisting 01' a matrix and a plurality ofdiamonds embedded in and protruding from said matrix, substantially allof said diamonds being positioned in one plane, said matrix consisting01' a sintered composition containing an appreciable amount of cobalt.

9. The method of setting diamonds or the like which comprises spacing aplurality of diamonds in a mold, applying to said diamonds a mixture ofcomminuted metallic material, which material has the property of closelyadhering to said diamonds when heated to an elevated temperature andsubsequently cooled, and then subjecting the mass to a temperature whichdoes not impair the. quality of said diamonds but is sufiiciently highto sinter the mass into a coherent product.

' GEORGE F. TAYLOR.

of metal or lower melting point

